In single pole N-throw radio-frequency (RF) switches, the insertion loss is degraded by the on-resistance of the switching active element (e.g. CMOS transistors, complementary metal-oxide-semiconductor transistor) and (N−1) times the parasitic capacitance of the off-ports in series with 1/(N−1) the resistance of the off-ports shunts, used to improve the port to port isolation. The resistance can be reduced by increasing the size (e.g. length or width) of the shunts and the capacitance is matched by external LC matching network. For antenna switching applications, for example, a parallel inductor is added for ESD protection and compensation of the parasitic capacitance at the low side frequency band while a serial inductor-parallel capacitor network is used for high band matching.
A drawback of some of the known switches is the high insertion loss. A drawback of some other known switches is the high number of discrete elements or external components.